Air venting device for the cylinder of a hydraulic vehicle lift



AEI 5, 1955 E. B. THOMPSON 2 705 5 2 AIR VENTING DEVICE FOR THE CYLINDER 7 o OF A HYDRAULIC VEHICLE LIFT Filed Nov. so, 1949 United States Patent O AIR VENTING DEVICE FOR THE CYLINDER F A HYDRAULIC VEHICLE LIFT Elmer B. Thompson, Des Moines, Iowa, assignor to Globe Hoist Company, Des Moines, Iowa, a corporation of Iowa Application November 30, 1949, Serial No. 130,335

1 Claim. (Cl. 137-202) This invention relates generally to hydraulic vehicle lifts and in particular to an air eliminating device for a vehicle lift of hydraulic type for venting air from the lift cylinder during a vehicle-elevating operation.

Hydraulic lifts usually include a cylinder having a lift piston guidably supported therein so as to leave an annular space between the piston and the cylinder. This space about the piston is closed by a fluid tight packing mounted about the upper end of the cylinder and the piston is elevated by the admission of oil under pressure to the cylinder at a position below the packing. After the lift has been installed and the piston is initially operated, provision must be made for the bleeding of air from the cylinder to assure a satisfactory and safe operation of the lift. Also in use, air leaking into the cylinder about the packing must be exhausted or vented from the cylinder to eliminate any air cushion or pocket therein.

It is an object of this invention, therefore, to provide an improved vehicle lift.

A further object of this invention is to provide an air exhaust or bleeder device for a hydraulic vehicle lift which is adapted to exhaust air from the lift cylinder concurrently with the admission of oil under pressure to the lift cylinder, so that no air remains in the cylinder when the lift piston is operated.

A further object of this invention is to provide an air bleeding device for the cylinder of a hydraulic vehicle lift which is of a construction such that oil under pressure admitted to the cylinder forces any air from the cylinder into the atmosphere, and with the oil being automatically stopped against ow into the atmosphere when the cylinder is free of air.

Still another object of this invention is to provide an air eliminating or bleeder device for a vehicle lift of hydraulic type which is of a simple and compact construction, efficient in operation to vent air from the lift cylinder at the beginning of every lifting operation, and capable of being readily and economically applied to hydraulic lifts now in general use.

A feature of this invention is found in the provision for a hydraulic vehicle lift having a cylinder and a piston therein operated by the admission of air under pressure to the cylinder, of an air bleeding device including a valve unit formed with a chamber means having an outlet at its upper end open to the atmosphere and an inlet adjacent its lower end fluid connected with the lift cylinder adjacent to the upper end thereof, with such iluid connection being inclined generally upwardly from the cylinder to the chamber means. A oat chamber in the chamber means, movable upwardly on the admission of oil into the chamber means, has its upper end engageable with a normally open valve member to close the same. The valve member controls the ow of fluid through the outlet of the chamber means so that when the air exhausted from the cylinder has passed therethrough, the valve member is closed by the float member to prevent the escape of oil from the cylinder.

Further objects, features and advantages of this invention will appear from the following description when talerlil in connection with the accompanying drawing, in w 1c Fig. l is a vertical sectional view of a hydraulic lift showing the air venting device of this invention in assembly relation therewith;

Fig. 2 is an enlarged vertical sectional view of the air venting device; and

Fig. 3 is an enlarged sectional detail view taken along the line 3--3 in Fig. 2.

With reference to the drawings, the air bleeder device of this invention, designated generally at 5, is illustrated in Fig. 1 in assembly relation with a hydraulic vehicle hoist having a ground-embedded cylinder 10 and an associated lift piston 11 mounted in a spaced relation therein so that an annular space 12 is formed between the piston and the cylinder. The piston 11 is guidably supported for up and down movement within the cylinder by a combination bearing and fluid tight packing unit 13, mounted about the upper end of the cylinder 10 and closing the top of the annular space 12. The lower end of the piston 11 carries a bearing ring 14 which is in guidable engagement with the inner peripheral surface of the cylinder 10. A super-structure or vehicle supporting frame 15 is suitably secured to the top of the piston 11.

In the operation of the piston 11 to raise a vehicle supported on the frame 15, oil under pressure is admitted into the cylinder 10 through an oil line 16 connected to an oil reservoir or tank 17 which is imbedded in the ground. The oil admitted to the cylinder 10 enters the annular space 12, and ows through ports 11a so as to exert an upward pressure on the piston base plate 35. The passage of oil through the line 16 is controlled by an oil valve unit 18 having a manually actuated handle 19, and the upward movement of the piston; is limited by the engagement of a piston stop ring 40 with the combination unit 13.

Pressure is applied on the oil within the tank 17 by compressed air admitted to the tank 17 above the level of the liquid of the oil therein through an air line 21 having an inlet 20 connected with an air compressor (not shown). Placed in the air line 21 is an air control valve 22, of a three-way type, having an actuating handle 23 movable to a tirst position to supply air under pressure to the tank 17, to a second position to maintain air under pressure within the tank 17, and to a third position to release the air from the tank 17 through an exhaust p0rtion 25. In the operation of the hoist to raise and lower the piston 11, the handle 19 for the oil control valve 1S, and the handle 23 for the air valve 22, are relatively operated in a well-known manner.

After the hoist has been installed, it will be apparent that the annular space 12 will be completely filled with air which must be expelled or vented from the cylinder 10 to provide for a satisfactory operation of the hoist. Further, in the normal operation of the hoist, oil will be lost through seepage, and air will leak through the packing 13 so as to make the presence of air within the cylinder 10 a continuing diflculty.

It is the purpose of the air bleeding device 5 of this invention to provide for a complete venting or exhausting of any air from the cylinder 10 at any ltime the hoist is to be operated, so that the cylinder 10 is free of air prior to any elevation or upward movement of the piston 11.

The device 5 includes an upright tubular valve casing member 26 (Fig. 2) having a lower reduced section 29 and an upper internally threaded open portion 27 of enlarged section. The reduced portion 29 of the casing 26 has a closed lower end 30 and its upper end is closed by a plug member 31 threadable within the enlarged section 27 so that a chamber 32 is formed within the reduced section 29. Extended centrally through the plug member 31 is an upright passage 34, the lower end of which terminates in a valve seat 36 for a ball valve member 37 having a cage member 38 of an open construction projected downwardly within the chamber 32.

Loosely extended through the lower end 39 of the cage member 38 is a uted valve actuating pin 41 (Figs. 2 and 3), the lower end of which is engageable with a tappet plug 42 projected upwardly from a float member 43 located within the chamber 32. On upward movement of the oat member 43, the actuating pin 41 is engaged and moved upwardly to in turn move the ball member 37 into closed engagement with its seat 36 whereby to close the passage 34 within the plug member 31. The upper end of the passage 34 is open to a space 44 formed between the plug member 31 and a second plug member 46 of a solid construction threadable within the enlarged portion 27 of the casing 26. The space 44 is provided with an outlet connection 28 which is open to the atmosphere.

The lower end of the chamber 32 is provided with an inlet 33 connected through a pipe connection 47 with the cylinder 10, as indicated at 48 (Fig. 1), at a position immediately below the fluid packing 13 and at the upper end of the annular space 12. From a consideration of Fig. 1, it is seen that the outlet 28 is vertically spaced from the inlet 33, and that the connection 48 of the pipe 47 with the cylinder 12 is below the level of the inlet 33.

In the operation of the air bleeder device 5, assume that oil under pressure is being supplied to the cylinder 10 to operate the piston 11. The oil thus introduced into the cylinder 10 moves any air within the space 12 toward the upper end thereof. This air passes outwardly from the cylinder 10 through the pipe connection 47 into the chamber 32, and through the normally open valve 37 into the passage 34 for travel through the space 44 and outlet 28 to the atmosphere. As the last of the air is vented or exhausted from the cylinder 12, it is followed by oil which travels upwardly in the pipe line 47 and into the chamber- 32. The oil entering the chamber 32 acts to move the float 43 upwardly into engagement with the actuating pin 41 to close the valve 37. On closing of the valve 37, a pressure of the oil within the cylinder 10 is built up for application against the base plate 35 of the piston 11 to raise the same.

On the lowering of the piston 11, oil is maintained within the pipe line 47 by the pressure applied on the oil by the lowering piston. However, in the event this pressure on the oil is removed, the oil from the line 47 is free to return by the action of gravity into the cylinder 10.

It is seen, therefore, that any air entering the cylinder 10, as the result of leakage about the packing 13, or through the air bleeding device 5, is immediately exhausted upon the introduction of oil under pressure to the cylinder 10 so that the space 12 is entirely free of air at the time the piston 11 is to be elevated in the raising of a vehicle.

Although the invention has been described with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited since changes can be made therein which are within the full intended scope of this invention, as defined by the appended claim.

I claim:

An air vent valve unit for positioning in a oor below the level of the top surface thereof comprising an upright casing having its bottom end closed and its top end open, a first plug member removably positioned in the open top end of said casing and having a passage extended therethrough, said passage having the ends thereof terminating in the top and bottom surfaces of said plug member, a float positioned in said casing below said first plug member, a valve member movably mounted independently of said iioat in said casing at a position between said oat and first plug member and operable by said oat to close the lower end of said passage, a second plug member removably mounted in the open top end of said casing at a position above said first plug member to form a space between said plug members, said casing having an inlet adjacent the lower end thereof and an outlet in a side wall thereof communicating with the space between said plug members, with said inlet being spaced above the bottom end of said casing so that the space within said casing below said inlet constitutes a fluid reservoir, and with said valve member and said float being removable through the open top end of said casing on removal of said plug members.

References Cited in the file of this patent UNITED STATES PATENTS Klemm June 11, 

